Forging press

ABSTRACT

In order to shorten the height of a hydraulic press and to provide a reliable two-point guide, there is a fixed cross-head and the cylinder of a press ram is fixed to the cross-head; the press piston carries the forging tool and retraction means such as a cross-piece and retraction rams act on the press piston rod to retract the press piston.

United States Patent Priebe Dec. 11, 1973 [54] FORGING PRESS I FOREIGN PATENTS OR APPLICATIONS lnvemorl Frill Priebe, Duisburg, Germany 477,298 6/1929 Germany 72/453 [73] Assignee: Schloemann Aktiengesellshaft, 1395576 M962 France Dusseldorf Germany 1,409,250 7/1965 France 10,164 5/1956 Germany 22 il 22 1971 674,113 4/1939 Germany 72/453 [21] Appl' 200957 Primary Examiner-Charles W. Lanham Assistant ExaminerGene P. Crosby [30] Foreign Application Priority Data Attorney-Holman & Stern Nov. 20, 1970 Germany P 20 56 994.2

[57] ABSTRACT 72/453 In order to shorten the height of a. hydraulic Press and [58] Fie'ld R to provide a reliable two-point guide, there is a fixed cross-head and the cylinder of a press ram is fixed to [56] References Cited the cross-head; the press piston carrIesthe forgIng tool and retract1on means such as a cross-pIece and retrac- UNITED STATES PATENTS tion rams act on the press piston rod to retract the 3,010,432 11/1961 Robra I 100/269 R press piston. 2,169,113 8/1939 Sheppard... 72 453 3,592,131 7 1971 Otsuka 100/269 R 3 Claims, 2 Drawing Flgllres PMENIEnnEc 11 ms 3377539 7 sum 10? 2 INVENTOR FRITZ PQIEBE PATENIEUI EB 1 1 ma 3.777539 SHEET 2 0F 2 fin-i IN V EN TOR FRITZ PQIEBE BY FORGING PRESS BACKGROUND OF THE INVENTION The present invention relates to a pressure fluid actuated (normally hydraulically actuated), preferably single-cylinder, forging press, in which a moving part of a press ram (piston and cylinder arrangement) fixed to a cross-head of a press carries a forging tool (e.g. a die) at one end and engages retraction means (e.g. a retraction cross-piece and a hydraulic retraction system) at the other end. In a conventional construction, for instance, as shown in US. Pat. No. 3,010,432, the press has main columns which are used as guides for a moving main cross-head which is fixed to the piston in order to guide the piston. The present invention, however, particularly relates to a forging press of a type which has no moving main cross-head fixed to the moving part of the press ram, for guiding the moving part of the press ram.

The main columns of the press frame are not used as guides, in order to avoid bending stresses in the columns when there is an eccentric forging load, and the wear and tear which would occur on the columns if they were used as guide members. The moving masses are also relatively small. The moving part of the press ram can be guided on two guides (i.e. at two guide locations) spaced apart in the axial direction of the press. The press can be of column or frame construction, and such presses normally have a platen arranged to carry a second forging tool for cooperating with the first forging tool.

In a prior forging press of the type described in German Pat. No. 1,134,261, the presscylinder in the press ram is designed to move up and down together with a moving cross-head which guides the press cylinder. A retraction cross-piece connected to the cylinder is, when the die is retracted, locatedat a distance from the cross-head which isequal to the stroke of the press. The fixed piston of the piston and cylinder arrangement projects out of the cylinder and is attached to a fixed cross-head by means of tie rods which extend through the retraction cross-piece.

The press cylinder carrying the die is guided at two guide locations, one on the moving cross-head and the other on the piston; during a stroke of the press, the two guide locations move closer to each other so that ultimately there is no stable and accurate two location (two-point) guide for the die. Securing the fixed piston by means of tie rods is not only costly but also increases the height of the press.

SUMMARY OF THE INVENTION The present invention provides a pressure fluid actuated press having a fixed cross-head,

a press ram having a press cylinder, a press piston and a piston rod connected to the press piston, the press cylinder being fixed to the fixed cross-head and the press piston being arranged for carrying a forging tool, and

retraction means for acting on the press piston rod to retract the press piston.

The retraction means preferably include a crosspiece cooperating with the press piston rod and pressure fluid means for retracting the crosspiece. The press can have aplaten arranged to carrya second forging tool for cooperating with the first forging tool and tensile members connecting the platen to the fixed cross-head.

In a press of the invention, the piston/piston rod unit is stepped and is subjected to fluid pressure on the annular face between the piston and the piston rod. This piston/piston rod unit constitutes the guide shaft and tool carrier and is the mainmovable weight of the press. Two guides bushings may advantageously be inserted in the press cylinder to constitute the only guide members. The press of the invention need have no tie rods and its maximum height can be: determined by the retracted retraction cross-piece. Thus, the height of the press can be less than in the conventional press referred to above, its construction can be less expensive and it can have a reliable two-point guide for the moving press piston.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hydraulic push-down forging press in accordance with the invention, shown in longitudinal section; and

FIG. 2 is a hydraulic push-up forging press in accordance with the invention, shown in longitudinal section.

DETAILED DESCRIPTION OF THE DRAWINGS The presses shown in FIGS. .1 and 2 have a rigid frame which is composed of a cylinder cross-head l, a base platen 2, columns 3 and nuts 4. A stationary press cylinder Sis held in the cylinder cross-head l by means of a securing ring 6. A stepped guide or press piston 7 has a piston rod 8 and an annular working face to which hydraulic fluid is supplied through a bore 9 in the press cylinder 5. The cylinder 5,- piston 7 and piston rod 8 constitute a press ram. On the large end face of the press piston 7 there is a protective plate 10 which holds in place a heat-reflecting, protective cage Ill and an upper die holder 12 (FIG. 1) or a lower die holder 13 FIG. 2

Connected to the piston rod 8 is a retraction crosspiece 14 with which there engage retraction pistons 15 which move in retraction cylinders 16, with the cylin ders 16 being in their turn mounted in the fixed cylinder cross-head 1. Two guide bushings l7, 18, which are located far apart in the press cylinder 5, form a reliable two-point guide for the stepped press piston 7. Packings 19, 20 seal the press cylinder 5 in relation tothe pressurized fluid.

The press with the push-down drive shown in FIG. 1 may be equipped with a sliding table 21 which carries the bottom die holder 13. The press rests on column bases 22 below the platen 2.

The press with the push'up drive shown in FIG. 2 cannot be equipped with a sliding table for the die holder 13-. Deflector members 23 on the bottom die here prevent scale falling through the opening in the floor (through which the die holder 13 projects). The push-up press rests on blocks 24 fixed to the cylinder cross-head l. The forging operation is, in this case, effected in an upwards direction. A forging S is positioned against the upper die by a crane or manipulator. It will be seen that in the presses of FIGS. 1' and 2, there is no moving cross-head to which the piston 7 is fixed for guiding the piston 7. The guide bushings l7, 18 are fixed in position and the distance apart of the guide cations does not alter as the piston 7 moves.

I claim:

1. A hydraulic forging press having a fixed cross-head,

a press ram having an internally stepped press cylinder, a press piston, a piston rod connected to the press piston, the piston rod being of smaller diameter than the press piston to define a step therebetween and the press cylinder having an internal wall defining a corresponding step, and means for admitting pressure fluid between said steps to actuate the piston, the press cylinder being fixed to the fixed crosshead and the press piston being for carrying a forging tool,

guide means within and adjacent one end of the cylinder for guiding the press piston, and further guide means within the other end of the cylinder, for

guiding the piston rod,

a platen for carrying a second forging tool for cooperating with the first forging tool,

tensile members connecting the platen to the fixed cross-head, and

retraction piston means for acting on the piston rod to retract the press piston.

2. The hydraulic press as claimed in claim 1, wherein the retraction piston means includes a cross-piece cooperating with the piston rod and pressure fluid means for retracting the cross-piece.

3. The hydraulic press as claimed in claim 1, wherein said guide means for guiding the press piston consist of two guide bushings in the press cylinder and cooperating cylindrical surfaces on the press piston and the piston rod, respectively. 

1. A hydraulic forging press having a fixed cross-head, a press ram having an internally stepped press cylinder, a press piston, a piston rod connected to the press piston, the piston rod being of smaller diameter than the press piston to define a step therebetween and the press cylinder having an internal wall defining a corresponding step, and means for admitting pressure fluid between said steps to actuate the piston, the press cylinder being fixed to the fixed crosshead and the press piston being for carryIng a forging tool, guide means within and adjacent one end of the cylinder for guiding the press piston, and further guide means within the other end of the cylinder, for guiding the piston rod, a platen for carrying a second forging tool for cooperating with the first forging tool, tensile members connecting the platen to the fixed cross-head, and retraction piston means for acting on the piston rod to retract the press piston.
 2. The hydraulic press as claimed in claim 1, wherein the retraction piston means includes a cross-piece cooperating with the piston rod and pressure fluid means for retracting the cross-piece.
 3. The hydraulic press as claimed in claim 1, wherein said guide means for guiding the press piston consist of two guide bushings in the press cylinder and cooperating cylindrical surfaces on the press piston and the piston rod, respectively. 